The optimal cell gap determination of a liquid crystal wavefront corrector from a single photoelectric measurement

It has been a crucial technique to improve the dynamic response characteristics of a liquid crystal wavefront corrector (LCWFC) with optimal cell gap since the LCWFC needs at least 2π (or π) phase modulation in adaptive optics systems (AOSs). We have given a complete process for obtaining the optimal cell gap accurately from a single photoelectric measurement, which can be conducted with a liquid crystal (LC) cell of any known thickness. This method has been analysed theoretically and confirmed experimentally by using a wedge-shaped cell; the experimental results match very well with the theoretical analysis. The response time of an optimal gap cell can be a novel evaluation method of response performance of LC materials.     

Comparisons of the vector method and tensor method for simulating liquid crystal devices

In calculating the director configuration in a liquid crystal device, two methods are commonly employed: a vector model and a tensor model. In this paper, we compare and contrast these methods for liquid crystal devices consisting of a layer of liquid crystal sandwiched between two plates. We compare the reliability and accuracy of the results, the speed of computation and the complexity of implementations of each method.     

Novel mesophases in fluorine substituted banana-shaped mesogens

A new homologous series of achiral banana-shaped mesogens ('Dn') has been synthesized and studied by the classical techniques (optical microscopy, differential scanning calorimetry, X-ray diffraction, miscibility studies and electro-optic investigations). The short homologues (D6-D8) exhibit a two-dimensional phase 'B1_x' different from a B1 phase with a rectangular lattice. The longer homologues (D9-D14) present a mesophase which displays the defects of the B7 phase of the PIMB-NO₂ compounds. Nevertheless the D9-D14 mesophase is not miscible with the B7 phase, and contrary to B7, exhibits a bistable behaviour ('ferroelectric' type) suggesting at least a B7 variant.     

Biotransformation of musk xylene in trout haemoglobin: dose–response and toxicokinetics of musk xylene metabolites haemoglobin adducts by gas chromatography-mass spectrometry

Musk xylene (MX) is frequently used as a fragrance in commercial toiletries. Biotransformation of MX into 4-amino-MX (4-AMX) and 2-amino-MX (2-AMX) metabolites in rainbow trout haemoglobin (Hb) has been described. The dose–response relationship and toxicokinetics of the metabolites as adducts in the Hb were determined by gas chromatography (GC)–electron capture negative chemical ionization (NCI)–mass spectrometry (MS), and GC–electron ionization (EI)–MS/MS, using selected ion monitoring (SIM). The trout were subjected to a single exposure of 0.010, 0.030, 0.10, and/or 0.30?mg?MX/g of fish. Hb samples were collected from exposed and control fish, and analysed subsequent to exposure at intervals of 24, 72, and 168?h. Alkaline hydrolysis released 4-AMX and 2-AMX metabolites from the Hb, and the solutes were extracted into n-hexane. The extracts were preconcentrated and analysed. The presence of the metabolites in the Hb extracts was confirmed based on agreement of similar mass spectral features from NCI/MS and EI-MS/MS spectra, and retention times of the metabolites with standards. The NCI/MS results were used for dose–response and toxicokinetics measurements. For dose–response, the concentrations of adducts of the metabolites increased with dosage, and a maximum adduct formation was observed at 0.10?mg?g^?1, beyond which it decreased. The average concentrations of 4-AMX and 2-AMX at a dosage of 0.10?mg?g^?1 were 700 and 7.4?ng?g^?1, respectively. For toxicokinetics, the concentration of the metabolites in the Hb reached a maximum in the 3 day sample after administration of MX. Further elimination of the metabolites exhibited kinetics with a half-life estimated to be 1–2 days, assuming first-order kinetics. Quantitations were made based on an internal standard and a calibration plot. In control samples, non-hydrolysed Hb, and reagent blank extracts, the metabolites were not detected. The limits of detection for 4-AMX and 2-AMX in the Hb were approximately 1.7 and 1.4?µg?L^?1, respectively, based on a signal-to-noise ratio of 3 with NCI/MS.     

LABVIEW下冲击试验测试信号分析模块的设计

根据GJB冲击环境试验测试要求,介绍LABVIEW平台下两类典型冲击信号分析模块的设计方法,主要讲述利用多图层叠加编程技术实现GJB150.18-1986标准规定的半正弦波与后峰锯齿波动态套容差曲线分析模块的设计以及利用递归算法实现冲击响应谱分析模块的设计。其次,采用资源DLL封装技术对LABVIEW编程实现的冲击信号分析模块进行封装,在其他编程语言中调用DLL实现冲击信号分析模块在其他编程语言中的功能链接。实践表明,LABVIEW图形化编程技术可快速实现两类冲击信号分析模块的设计,将高速数据采集模块与冲击信号分析模块集成,可有效完成冲击试验测试与信号分析处理任务。     

基于层次分析法的企业网络舆情危机应对评价研究

网络舆情危机应对评价是企业在新的舆论背景下研究危机应对的重点.采用定量和定性分析有机结合的层次分析法确定指标体系及权重,给出了企业网络舆情危机应对评价的步骤,并进行了评价验证.该评价体系为相关单位网络舆情危机应对评价提供一定的参考和指导.     

Consequences of weak Allee effect on prey in the May–Holling–Tanner predator–prey model

In this work, a modified Holling–Tanner predator–prey model is analyzed, considering important aspects describing the interaction such as the predator growth function is of a logistic type; a weak Allee effect acting in the prey growth function, and the functional response is of hyperbolic type. Making a change of variables and time rescaling, we obtain a polynomial differential equations system topologically equivalent to the original one in which the non‐hyperbolic equilibrium point (0,0) is an attractor for all parameter values. An important consequence of this property is the existence of a separatrix curve dividing the behavior of trajectories in the phase plane, and the system exhibits the bistability phenomenon, because the trajectories can have different ω ? limit sets; as example, the origin (0,0) or a stable limit cycle surrounding an unstable positive equilibrium point. We show that, under certain parameter conditions, a positive equilibrium may undergo saddle‐node, Hopf, and Bogdanov–Takens bifurcations; the existence of a homoclinic curve on the phase plane is also proved, which breaks in an unstable limit cycle. Some simulations to reinforce our results are also shown. Copyright © 2015 John Wiley & Sons, Ltd.     

Global stability of humoral immunity virus dynamics models with nonlinear infection rate and removal

In this paper, we investigate the dynamical behavior of two nonlinear models for viral infection with humoral immune response. The first model contains four compartments; uninfected target cells, actively infected cells, free virus particles and B cells. The intrinsic growth rate of uninfected cells, incidence rate of infection, removal rate of infected cells, production rate of viruses, neutralization rate of viruses, activation rate of B cells and removal rate of B cells are given by more general nonlinear functions. The second model is a modification of the first one by including an eclipse stage of infected cells. We assume that the latent-to-active conversion rate is also given by a more general nonlinear function. For each model we derive two threshold parameters and establish a set of conditions on the general functions which are sufficient to determine the global dynamics of the models. By using suitable Lyapunov functions and LaSalle’s invariance principle, we prove the global asymptotic stability of the all equilibria of the models. We perform some numerical simulations for the models with specific forms of the general functions and show that the numerical results are consistent with the theoretical results.     

A Simple Approach for Multi‐fidelity Experimentation Applied to Financial Engineering

In practical applications, information about the accuracy or ‘fidelity’ of alternative surrogate systems may be ambiguous and difficult to determine. To address this problem, we propose to treat surrogate system fidelity level as a categorical factor in optimal response surface design. To design the associated experiments, we apply the Expected Integrated Mean Squared Error optimal design criterion, which takes into account both variance and bias errors. The performance of the proposed design was compared using three test cases to four types of alternatives using the Empirical Integrated Squared Error. Because of its ability to foster relatively accurate predictions, the proposed design is recommended in fidelity experimental design, particularly when the experimenters lack sufficient information about the fidelity levels of surrogate systems. The method was applied to the case of intraday trading optimization in which data were collected from the Taiwan Futures Exchange. We also calculated the implied volatility from the Merton's Jump‐diffusion model via the fast Fourier transform algorithm with three different models of varying fidelity levels. Copyright © 2014 John Wiley & Sons, Ltd.     

A general,recursive, and open‐ended response code

We present a new implementation of a recent open‐ended response theory formulation for time‐ and perturbation‐dependent basis sets (Thorvaldsen et al., J. Chem. Phys. 2008, 129, 214108) at the Hartree–Fock and density functional levels of theory. A novel feature of the new implementation is the use of recursive programming techniques, making it possible to write highly compact code for the analytic calculation of any response property at any valid choice of rule for the order of perturbation at which to include perturbed density matrices. The formalism is expressed in terms of the density matrix in the atomic orbital basis, allowing the recursive scheme presented here to be used in linear‐scaling formulations of response theory as well as with two‐ and four‐component relativistic wave functions. To demonstrate the new code, we present calculations of the third geometrical derivatives of the frequency‐dependent second hyperpolarizability for HSOH at the Hartree–Fock level of theory, a seventh‐order energy derivative involving basis sets that are both time and perturbation dependent. © 2014 Wiley Periodicals, Inc.